Defending Marijuana Impaired Driving Cases
Experienced-Based Strategies For Defending Marijuana Impaired/Intoxicated Driving Cases
Michael Horowitz has taken numerous DUI/OUI cases involving substances to trial. Attorney Horowitz has tried impaired/intoxicated driving cases involving opiates, muscle relaxers, anxiety medicine, methamphetamine, heroin, and, of course, marijuana. Through these trials, Attorney Horowitz has honed strategies to successfully handle impaired driving cases. Some of the more important things Attorney Horowitz has learned specifically regarding marijuana impairment cases are explained in detail below.
Michigan legalized marijuana. It is still illegal to drive while impaired by marijuana.Being able to legally possess and consume marijuana does not make it legal to drive after consuming marijuana. Remember: Alcohol is legal to consume and possess. Obviously you can be charged with drinking and driving.
The act that legalized marijuana is the “Michigan Regulation and Taxation of Marihuana Act.” Section 4.1 of that act specifically provides:
This act does not authorize:
(a) operating, navigating, or being in physical control of any motor vehicle, aircraft, snowmobile, off-road recreational vehicle, or motorboat while under the influence of marihuana . . . .
Additionally, Michigan’s OUI/OWI statute provides, in part, that:
(1) A person, whether licensed or not, shall not operate a vehicle upon a highway or other place open to the general public or generally accessible to motor vehicles, including an area designated for the parking of vehicles, within this state if the person is operating while intoxicated. As used in this section, “operating while intoxicated” means any of the following:
(a) The person is under the influence of alcoholic liquor, a controlled substance, or other intoxicating substance or a combination of alcoholic liquor, a controlled substance, or other intoxicating substance.
(b) The person has an alcohol content of 0.08 grams or more per 100 milliliters of blood, per 210 liters of breath, or per 67 milliliters of urine or, beginning October 1, 2021, the person has an alcohol content of 0.10 grams or more per 100 milliliters of blood, per 210 liters of breath, or per 67 milliliters of urine.
(3) A person, whether licensed or not, shall not operate a vehicle upon a highway or other place open to the general public or generally accessible to motor vehicles, including an area designated for the parking of vehicles, within this state when, due to the consumption of alcoholic liquor, a controlled substance, or other intoxicating substance, or a combination of alcoholic liquor, a controlled substance, or other intoxicating substance, the person's ability to operate the vehicle is visibly impaired.
(8) A person, whether licensed or not, shall not operate a vehicle upon a highway or other place open to the general public or generally accessible to motor vehicles, including an area designated for the parking of vehicles, within this state if the person has in his or her body any amount of a controlled substance listed in schedule 1 under section 7212 of the public health code, 1978 PA 368, MCL 333.7212, or a rule promulgated under that section, or of a controlled substance described in section 7214(a)(iv) of the public health code, 1978 PA 368, MCL 333.7214.
THC Absorption and Elimination (how long does active THC stay in your system)
I am emphatically not a doctor or scientist, but I have tried enough drug impairment trials at this point to be familiar with the commonly relied upon materials and with the consistent themes of expert witness testimony. I have tried and won trials involving the rate that alcohol or other chemicals enter the bloodstream (absorption) and the rate at which those chemicals leave the bloodstream (elimination). I have cross-examined numerous state crime lab toxicologists about this issue and I have also presented my own expert witnesses in the form of medical doctors, toxicologists, and pharmacologists.
Regarding marijuana, or more specifically, active THC (tetrahydrocannabinol), I have observed through these various source materials and experts that the absorption and elimination of THC from normal marijuana inhalation is commonly said to follow a predictable rate. For example, according to the National Center for Biotechnology Information,an average person that inhaled an average dosage of THC would have their THC peak in 8 minutes and then decrease to 1-4ng/ml 3 to 4 hours later.
So the THC peaks very rapidly, decreases less rapidly, and then sort of trails off around 1-4 ng/ml a few hours later. As applied to defending a marijuana-based DUI/OUI, this rate has a couple of implications.
First, if a chemical test of someone’s blood shows more than around 10ng/ml, I think it’s safe to assume that a prosecutor will argue that the person had ingested marijuana shortly before being pulled over, and was thus impaired. Assuming an officer performs a normal traffic stop and investigation, conducts field-sobriety tests, transports the driver to a hospital for a blood draw, and then has a nurse or phlebotomist take a blood sample, the sample will likely be collected an hour or two after the last possible time the driver could have ingested marijuana. So looking at the rate of absorption and elimination, a THC level of around 10 ng/ml or higher would suggest the driver ingested marijuana several hours before the sample was taken. Subtract from that the time elapsed since the traffic stop, and it looks like the driver inhaled marijuana not too long before being stopped.
Second, the time for active THC to be completely eliminated is indeterminate. The study cited above says that, on average, THC will decrease to 1–4 ng/ml within 3–4 hours later. Notice, however, that it does not decrease to ZERO. Looking at the rough chart above, what I tried to capture was many experts’ testimony that the rate of elimination decreases over time such that some amount of active THC may remain in a person’s blood indefinitely. This could mean that a casual smoker might have someamount of active THC remaining in their blood 10 hours or a day after smoking. In fact, according to some studies and some of the experts I have worked with, chronic users may have an “ambient” THC level in excess of 2ng/ml all the time. Applied to the criminal defense of a marijuana-based DUI/OUI or other criminal charge, the indefinite presence of a small amount of active THC means 1) marijuana users are indefinitely at risk of being charged with OUI/DUI, and 2) the defense attorney must be prepared to evaluate and argue that the low amount of THC does not indicate recent consumption or impairment.
Active THC vs. Inactive THC
While reading the above discussion on marijuana absorption and elimination in the OUI/DUI context, you may have questioned why I kept referring to “active THC.” Marijuana contains various chemical compounds, but the one that we’re predominately concerned about in the OWI/DUI context is tetrahydrocannabinol, or THC.
The NCBI article cited above explains that “[t]he primary psychoactive constituent of cannabis, delta 9-tetrahydrocannabinol (▵9 THC), produces a myriad of pharmacological effects in animals and humans.” This is “active” THC. Once the body metabolizes (breaks down) this active THC, a portion is converted to carboxy THC ( often listed on toxicology reports as “THC-COOH” or “11–carboxy–THC”). This is “inactive” THC.
While active THC is generally eliminated in the timeframe discussed above, inactive THC can remain detectable in the consumer’s blood or urine for much longer, even months. With respect to driving and DUI/OUI, Michigan distinguishes between “active” THC and “inactive” THC. In People v Feezel,486 Mich 184, 208; 783 NW2d 67, 82 (2010), the Michigan Supreme Court noted that “11–carboxy–THC has no known pharmacological effect” and that experts in a prior case agreed that “11–carboxy–THC itself has no pharmacological effect on the body and its level in the blood correlates poorly, if at all, to an individual's level of THC-related impairment.” The court then explicitly held that 11–carboxy–THC is not a schedule 1 controlled substance and thus could not a support a conviction under MCL 257.625(4) and (8). Id.at 211–12. Thus, in Michigan, a driver can be convicted of OUI for operating with someamount of active THC in their system, but they likely cannot be convicted based solely upon inactive THC.
How much is too much? Can I be convicted of OUI/DUI?
The safe answer is having any THC in a driver’s bloodstream is too much to drive. However, based on the above information about eliminations rates, this might not be reasonable. If a chronic user can have someamount of THC in their bloodstream at all times, and if a casual smoker could have someamount of THC in their bloodstream the day after smoking, what does that mean for their ability to drive a car? Well, one of the biggest problems with marijuana-based OUI/DUI is that there is no generally accepted level of THC. (Some states have per se THC limits. Michigan does not. These limits aren’t particularly helpful.)
So if there’s no legal limit, how does a prosecutor prove that a driver is guilty of marijuana-based DUI/OUI? The prosecutor will have to point to other factors, which in the criminal justice world we refer to as “indicia of impairment.” These indicia include how a driver speaks, acts, moves; whether the person has bloodshot and watery eyes or an eye movement called “nystagmus”; how the driver performs on field-sobriety tests; how the driver was driving (i.e., what was the reason for the stop, was the driver swerving); and any admissions of consumption. Most of the time a patrol officer or trooper will have some sort of audio or video recording of the traffic stop, so at least some of these indicia could be presented to a jury. The indicia that are not recordable — e.g., bloodshot watery eyes, nystagmus, odor of marijuana — can be presented to the jury through the officer’s testimony, subject of course to cross-examination by the defense attorney.
My shorthand way of explaining likely outcomes to clients or potential clients is this: the numbers probably won’t mean that much to a jury, but if a driver looks or sounds stoned, high, or otherwise impaired on the audio or video recording, the jury is going to conclude that driver was indeed stoned, high, or otherwise impaired, and will thus convict the driver of some form of OUI/DUI. So from the defense prospective, the driver’s attorney will have to convincingly show the jury why the prosecutor’s evidence does not show impairment (e.g., “Look at how well he did on that walk-and-turn test!” or “Listen to how clearly he counted to 30 while keeping his balance!”).
“Marijuana” or “Marihuana”
No, “marihuana” is not a typo. In Michigan, federal jurisdictions, and some other states, the laws and court cases spell marijuana with an H. The best I can tell, it’s still pronounced the same. Essentially, it’s just a holdover from a long time ago where English speakers wrote the “ju” sound as “hu.”
Marijuana Impaired Driving Resources
Attorney Horowitz is not a doctor, medical professional, toxicologist, chemist, pharmacologist, or any type of scientist. Nothing on this page is intended as medical or legal advice.
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The Law Office of Michael Horowitz is located in the ABS Building, the newly renovated building with the American Flag/Eagle-shingled roof right off the Brownson/M-113 intersection in downtown Kingsley (behind Thirlby Automotive and across M-113 from Subway).
108 E. Main St. Kingsley, MI 49649